The Si Tian project,designed to utilize 60 telescopes distributed across multiple sites in China,is a next-generation timedomain survey initiative.As a pathfinder for the Si Tian project,the Mini-Si Tian(MST)has been ...The Si Tian project,designed to utilize 60 telescopes distributed across multiple sites in China,is a next-generation timedomain survey initiative.As a pathfinder for the Si Tian project,the Mini-Si Tian(MST)has been proposed and implemented to test the Si Tian’s brain and data pipeline,and to evaluate the feasibility of its technology and science cases.Mounted at the Xinglong Observatory,the MST project comprises three 30 cm telescopes and has been operated since 2022 November.Each telescope of the MST possesses a large field of view,covering 2°.29×1°.53 FOV,and is equipped withg',r'andi'filters,respectively.Acting as the pioneer of the forthcoming Si Tian project,the MST is dedicated to the discovery of variable stars,transients,and outburst events,and has already obtained some interesting scientific results.In this paper,we will summarize the first-two-year operation of the MST project.展开更多
Adaptive optics(AO)has significantly advanced high-resolution solar observations by mitigating atmospheric turbulence.However,traditional post-focal AO systems suffer from external configurations that introduce excess...Adaptive optics(AO)has significantly advanced high-resolution solar observations by mitigating atmospheric turbulence.However,traditional post-focal AO systems suffer from external configurations that introduce excessive optical surfaces,reduced light throughput,and instrumental polarization.To address these limitations,we propose an embedded solar adaptive optics telescope(ESAOT)that intrinsically incorporates the solar AO(SAO)subsystem within the telescope's optical train,featuring a co-designed correction chain with a single Hartmann-Shack full-wavefront sensor(HS f-WFS)and a deformable secondary mirror(DSM).The HS f-WFS uses temporal-spatial hybrid sampling technique to simultane-ously resolve tip-tilt and high-order aberrations,while the DSM performs real-time compensation through adaptive modal optimization.This unified architecture achieves symmetrical polarization suppression and high system throughput by min-imizing optical surfaces.A 600 mm ESAOT prototype incorporating a 12×12 micro-lens array HS f-WFS and 61-actuator piezoelectric DSM has been developed and successfully conducted on-sky photospheric observations.Validations in-cluding turbulence simulations,optical bench testing,and practical observations at the Lijiang observatory collectively confirm the system's capability to maintain aboutλ/10 wavefront error during active region tracking.This architectural breakthrough of the ESAOT addresses long-standing SAO integration challenges in solar astronomy and provides scala-bility analyses confirming direct applicability to the existing and future large solar observation facilities.展开更多
We report the confirmation of a sub-Saturn-size exoplanet,TOI-1194 b,with a mass of about 0.456+0.055-0.051M_(J),and a very low mass companion star with a mass of about 96.5±1.5 MJ,TOI-1251 B.Exoplanet candidates...We report the confirmation of a sub-Saturn-size exoplanet,TOI-1194 b,with a mass of about 0.456+0.055-0.051M_(J),and a very low mass companion star with a mass of about 96.5±1.5 MJ,TOI-1251 B.Exoplanet candidates provided by the Transiting Exoplanet Survey Satellite(TESS)are suitable for further follow-up observations by ground-based telescopes with small and medium apertures.The analysis is performed based on data from several telescopes worldwide,including telescopes in the Sino-German multiband photometric campaign,which aimed at confirming TESS Objects of Interest(TOIs)using ground-based small-aperture and medium-aperture telescopes,especially for long-period targets.TOI-1194 b is confirmed based on the consistent periodic transit depths from the multiband photometric data.We measure an orbital period of 2.310644±0.000001 days,the radius is 0.767+0.045-0.041RJ and the amplitude of the RV curve is 69.4_(-7.3)^(+7.9)m s^(-1).TOI-1251 B is confirmed based on the multiband photometric and high-resolution spectroscopic data,whose orbital period is 5.963054+0.000002-0.000001days,radius is 0.947+0.035-0.033 R_(J) and amplitude of the RV curve is 9849_(-40)^(+42)ms^(-1).展开更多
The[O iii]λλ4960,5008 emission lines in the optical spectra of galaxies and quasars have been widely used to investigate the possible variation of the fine-structure constantαover cosmic time.In this work,we utiliz...The[O iii]λλ4960,5008 emission lines in the optical spectra of galaxies and quasars have been widely used to investigate the possible variation of the fine-structure constantαover cosmic time.In this work,we utilize the Large Sky Area Multi-object Fiber Spectroscopic Telescope(LAMOST)quasar survey,for the first time,to measure the relativeαvariationΔα/αin time through the[O iii]doublet method.From the LAMOST Data Release 9 quasar catalog,we refine a sample of 209 quasar spectra with strong and narrow[O iii]emission lines over a redshift range of 0<z<0.8.Analysis on all of the 209 spectra obtainsΔα/α=(0.5±3.7)×10^(−4),which suggests that there is no evidence of varyingαon the explored cosmological timescales.Assuming a linear variation,the mean rate of change inΔα/αis limited to be(−3.4±2.4)×10^(−13)yr^(−1)in the last 7.0 Gyr.While our LAMOST-based constraint on Δα/α is not competitive with those of the Sloan Digital Sky Survey(SDSS)quasar observations,our analysis serves to corroborate the results of SDSS with another independent survey.展开更多
There are extremely luminous quasi stellar objects （QSOs） at high redshift which are absent at low redshift. The lower luminosities at low redshifts can be understood as the external manifestation of either a lower ...There are extremely luminous quasi stellar objects （QSOs） at high redshift which are absent at low redshift. The lower luminosities at low redshifts can be understood as the external manifestation of either a lower Eddington ratio or a lower mass. To distinguish between both effects, we determine the possible dependence of masses and Eddington ratios of QSOs with a fixed luminosity as a function of redshifts; this avoids the Malmquist bias or any other selection effect. For the masses and Eddington ratios derived for a sample of QSOs in the Sloan Digital Sky Survey, we model their evolution by a double linear fit separating the dependence on redshifts and luminosities. The validity of the fits and possible systematic effects were tested by the use of different estimators of masses or bolometric luminosities, and possible intergalactic extinction effects. The results do not show any significant evolution of black hole masses or Eddington ratios for equal luminosity QSOs. The black hole mass only depends on the bolometric luminosity without significant dependence on the redshift as （M BH/10 9 M ）≈ 3.4 （L bol/10 47 erg s-1）0.65 on average for z ≤ 5. This must not be confused with the possible evolution in the formation of black holes in QSOs. The variations of the environment might influence the formation of the black holes but not their subsequent accretion. It also leaves a question to be solved： Why are there not QSOs with very high mass at low redshift？ A brief discussion of the possible reasons for this is tentatively pointed out.展开更多
The largest ground-based telescopes will be much larger than their space-based counterparts far into the future.Remote sensing problems that can take advantage of active and adaptive wavefront control that correct the...The largest ground-based telescopes will be much larger than their space-based counterparts far into the future.Remote sensing problems that can take advantage of active and adaptive wavefront control that correct the incoming atmospherically distorted optical wavefront can benefit from very large ground-based telescopes that have other important advantages.For example,their much lower cost(typically one or two orders of magnitude less)and shorter time-to-completion can be compelling.For optical or IR problems that require high angular resolution and large photometric dynamic range we suggest that techniques that make use of photonics,machine learning,or additive manufacturing may even enable less expensive specialized telescopes that are larger than what astronomers are currently building.The Instituto de Astrofísica de Canarias(IAC)recently began a 5 year program with support from the European Union called the Laboratory for Innovation in Opto-mechanics.Its goal is to show how technology innovations can enable less costly and larger telescopes,in particular,aimed at the problem of finding extrasolar life within a few parsecs of the Sun.展开更多
In this White Paper we present the potential of the enhanced X-ray Timing and Polarimetry(eXTP) mission for studies related to Observatory Science targets. These include flaring stars, supernova remnants, accreting wh...In this White Paper we present the potential of the enhanced X-ray Timing and Polarimetry(eXTP) mission for studies related to Observatory Science targets. These include flaring stars, supernova remnants, accreting white dwarfs, low and high mass X-ray binaries, radio quiet and radio loud active galactic nuclei, tidal disruption events, and gamma-ray bursts. eXTP will be excellently suited to study one common aspect of these objects: their often transient nature. Developed by an international Consortium led by the Institute of High Energy Physics of the Chinese Academy of Science, the eXTP mission is expected to be launched in the mid 2020s.展开更多
The Standard Model(SM)of particle physics succeeds in predicting the vast majority of experimental high-energy data in terms of a minimal set of subatomic particles and their strong and electroweak interactions.Howeve...The Standard Model(SM)of particle physics succeeds in predicting the vast majority of experimental high-energy data in terms of a minimal set of subatomic particles and their strong and electroweak interactions.However,while it is a selfconsistent theory.展开更多
基金supported by the National Key R&D Program of China(grant No.2023YFA1608304 and No.2023YFA1608300)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB0550100 and XDB0550000)the National Natural Science Foundation of China(NSFC,grant Nos.12090041,12090040,11903054,12422303,and 12261141690)。
文摘The Si Tian project,designed to utilize 60 telescopes distributed across multiple sites in China,is a next-generation timedomain survey initiative.As a pathfinder for the Si Tian project,the Mini-Si Tian(MST)has been proposed and implemented to test the Si Tian’s brain and data pipeline,and to evaluate the feasibility of its technology and science cases.Mounted at the Xinglong Observatory,the MST project comprises three 30 cm telescopes and has been operated since 2022 November.Each telescope of the MST possesses a large field of view,covering 2°.29×1°.53 FOV,and is equipped withg',r'andi'filters,respectively.Acting as the pioneer of the forthcoming Si Tian project,the MST is dedicated to the discovery of variable stars,transients,and outburst events,and has already obtained some interesting scientific results.In this paper,we will summarize the first-two-year operation of the MST project.
基金support from the National Science Foundation of China(NSFC)(Grants No.12293031 and No.61905252)the National Science Foundation for Distinguished Young Scholars(Grant No.12022308)the National Key R&D Program of China(Grants No.2021YFC2202200 and No.2021YFC2202204).
文摘Adaptive optics(AO)has significantly advanced high-resolution solar observations by mitigating atmospheric turbulence.However,traditional post-focal AO systems suffer from external configurations that introduce excessive optical surfaces,reduced light throughput,and instrumental polarization.To address these limitations,we propose an embedded solar adaptive optics telescope(ESAOT)that intrinsically incorporates the solar AO(SAO)subsystem within the telescope's optical train,featuring a co-designed correction chain with a single Hartmann-Shack full-wavefront sensor(HS f-WFS)and a deformable secondary mirror(DSM).The HS f-WFS uses temporal-spatial hybrid sampling technique to simultane-ously resolve tip-tilt and high-order aberrations,while the DSM performs real-time compensation through adaptive modal optimization.This unified architecture achieves symmetrical polarization suppression and high system throughput by min-imizing optical surfaces.A 600 mm ESAOT prototype incorporating a 12×12 micro-lens array HS f-WFS and 61-actuator piezoelectric DSM has been developed and successfully conducted on-sky photospheric observations.Validations in-cluding turbulence simulations,optical bench testing,and practical observations at the Lijiang observatory collectively confirm the system's capability to maintain aboutλ/10 wavefront error during active region tracking.This architectural breakthrough of the ESAOT addresses long-standing SAO integration challenges in solar astronomy and provides scala-bility analyses confirming direct applicability to the existing and future large solar observation facilities.
基金supported by National Natural Science Foundation of China(NSFC,Grant Nos.U1831209 and U2031144)the research fund of Ankara University(BAP)through the project 18A0759001。
文摘We report the confirmation of a sub-Saturn-size exoplanet,TOI-1194 b,with a mass of about 0.456+0.055-0.051M_(J),and a very low mass companion star with a mass of about 96.5±1.5 MJ,TOI-1251 B.Exoplanet candidates provided by the Transiting Exoplanet Survey Satellite(TESS)are suitable for further follow-up observations by ground-based telescopes with small and medium apertures.The analysis is performed based on data from several telescopes worldwide,including telescopes in the Sino-German multiband photometric campaign,which aimed at confirming TESS Objects of Interest(TOIs)using ground-based small-aperture and medium-aperture telescopes,especially for long-period targets.TOI-1194 b is confirmed based on the consistent periodic transit depths from the multiband photometric data.We measure an orbital period of 2.310644±0.000001 days,the radius is 0.767+0.045-0.041RJ and the amplitude of the RV curve is 69.4_(-7.3)^(+7.9)m s^(-1).TOI-1251 B is confirmed based on the multiband photometric and high-resolution spectroscopic data,whose orbital period is 5.963054+0.000002-0.000001days,radius is 0.947+0.035-0.033 R_(J) and amplitude of the RV curve is 9849_(-40)^(+42)ms^(-1).
基金supported by the National Natural Science Foundation of China(grant Nos.12422307,12373053,and 12321003)the Key Research Program of Frontier Sciences(grant No.ZDBS-LY-7014)+1 种基金Chinese Academy of Sciences,and the Natural Science Foundation of Jiangsu Province(grant No.BK20221562)supported by the Chinese Academy of Sciences President's International Fellowship Initiative(grant No.2023VMB0001)。
文摘The[O iii]λλ4960,5008 emission lines in the optical spectra of galaxies and quasars have been widely used to investigate the possible variation of the fine-structure constantαover cosmic time.In this work,we utilize the Large Sky Area Multi-object Fiber Spectroscopic Telescope(LAMOST)quasar survey,for the first time,to measure the relativeαvariationΔα/αin time through the[O iii]doublet method.From the LAMOST Data Release 9 quasar catalog,we refine a sample of 209 quasar spectra with strong and narrow[O iii]emission lines over a redshift range of 0<z<0.8.Analysis on all of the 209 spectra obtainsΔα/α=(0.5±3.7)×10^(−4),which suggests that there is no evidence of varyingαon the explored cosmological timescales.Assuming a linear variation,the mean rate of change inΔα/αis limited to be(−3.4±2.4)×10^(−13)yr^(−1)in the last 7.0 Gyr.While our LAMOST-based constraint on Δα/α is not competitive with those of the Sloan Digital Sky Survey(SDSS)quasar observations,our analysis serves to corroborate the results of SDSS with another independent survey.
基金provided by the Alfred P. Sloan Foundationthe Participating Institutions+4 种基金the National Aeronautics and Space Administrationthe National Science Foundationthe U.S. Department of Energythe Japanese Monbukagakusho and the Max Planck Societysupported by the grant AYA2007-67625-CO2-01 of the Spanish Science Ministry
文摘There are extremely luminous quasi stellar objects （QSOs） at high redshift which are absent at low redshift. The lower luminosities at low redshifts can be understood as the external manifestation of either a lower Eddington ratio or a lower mass. To distinguish between both effects, we determine the possible dependence of masses and Eddington ratios of QSOs with a fixed luminosity as a function of redshifts; this avoids the Malmquist bias or any other selection effect. For the masses and Eddington ratios derived for a sample of QSOs in the Sloan Digital Sky Survey, we model their evolution by a double linear fit separating the dependence on redshifts and luminosities. The validity of the fits and possible systematic effects were tested by the use of different estimators of masses or bolometric luminosities, and possible intergalactic extinction effects. The results do not show any significant evolution of black hole masses or Eddington ratios for equal luminosity QSOs. The black hole mass only depends on the bolometric luminosity without significant dependence on the redshift as （M BH/10 9 M ）≈ 3.4 （L bol/10 47 erg s-1）0.65 on average for z ≤ 5. This must not be confused with the possible evolution in the formation of black holes in QSOs. The variations of the environment might influence the formation of the black holes but not their subsequent accretion. It also leaves a question to be solved： Why are there not QSOs with very high mass at low redshift？ A brief discussion of the possible reasons for this is tentatively pointed out.
基金funding from the European Union,Project Ref.:101087032support from the Agencia Estatal de Investigación del Ministerio de Ciencia e Innovación(AEI-MCINN)under grants PID2019-109522GB-C53 and PID2022-137241NB-C41.
文摘The largest ground-based telescopes will be much larger than their space-based counterparts far into the future.Remote sensing problems that can take advantage of active and adaptive wavefront control that correct the incoming atmospherically distorted optical wavefront can benefit from very large ground-based telescopes that have other important advantages.For example,their much lower cost(typically one or two orders of magnitude less)and shorter time-to-completion can be compelling.For optical or IR problems that require high angular resolution and large photometric dynamic range we suggest that techniques that make use of photonics,machine learning,or additive manufacturing may even enable less expensive specialized telescopes that are larger than what astronomers are currently building.The Instituto de Astrofísica de Canarias(IAC)recently began a 5 year program with support from the European Union called the Laboratory for Innovation in Opto-mechanics.Its goal is to show how technology innovations can enable less costly and larger telescopes,in particular,aimed at the problem of finding extrasolar life within a few parsecs of the Sun.
基金supported by the Royal Society,ERC Starting(Grant No.639217)he European Union Horizon 2020 Research and Innovation Programme under the Marie Sklodowska-Curie Global Fellowship(Grant No.703916)+10 种基金the National Natural Science Foundation of China(Grant Nos.11233001,11773014,11633007,11403074,11333005,11503008,and 11590781)the National Basic Research Program of China(Grant No.2015CB857100)NASA(Grant No.NNX13AD28A)an ARC Future Fellowship(Grant No.FT120100363)the National Science Foundation(Grant No.PHY-1430152)the Spanish MINECO(Grant No.AYA2016-76012-C3-1-P)the ICCUB(Unidad de Excelencia’Maria de Maeztu’)(Grant No.MDM-2014-0369)EU’s Horizon Programme through a Marie Sklodowska-Curie Fellowship(Grant No.702638)the Polish National Science Center(Grant Nos.2015/17/B/ST9/03422,2015/18/M/ST9/00541,2013/10/M/ST9/00729,and 2015/18/A/ST9/00746)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA15020100)the NWO Veni Fellowship(Grant No.639.041.647)
文摘In this White Paper we present the potential of the enhanced X-ray Timing and Polarimetry(eXTP) mission for studies related to Observatory Science targets. These include flaring stars, supernova remnants, accreting white dwarfs, low and high mass X-ray binaries, radio quiet and radio loud active galactic nuclei, tidal disruption events, and gamma-ray bursts. eXTP will be excellently suited to study one common aspect of these objects: their often transient nature. Developed by an international Consortium led by the Institute of High Energy Physics of the Chinese Academy of Science, the eXTP mission is expected to be launched in the mid 2020s.
基金support from the Spanish MINECO through the“Ramón y Cajal”Program RYC-2016–20672 and the PGC2018-102016-A-I00support from the UK Science and Technology Facilities Council(STFC)。
文摘The Standard Model(SM)of particle physics succeeds in predicting the vast majority of experimental high-energy data in terms of a minimal set of subatomic particles and their strong and electroweak interactions.However,while it is a selfconsistent theory.
